In 2008, California voters passed a ballot measure that took the responsibility of drawing legislative districts out of the hands of politicians and entrusted it to a bipartisan commission.
Using the figures from the 2010 census, the California Citizens Redistricting Commission drew up a new set of lines that, unsurprisingly in a state that heavily favors Democrats, heavily favored Democrats. Some Republicans feared the new districts would endanger the one-third of seats in the state senate the party needs to block the passage of any new taxes, so they put a measure on the ballot mandating the California Supreme Court appoint a "special master" to determine new state senate districts.
Here's where it gets complicated, so pay attention: Prop 40 is a referendum on maintaining the original 2008 redistricting ballot measure, meaning that a yes vote would keep the system the way it is now and a no vote would mean changing the way the lines are drawn. Yes, the people who put Prop 40 on the ballot wanted everyone to vote against it. Sigh.
Those pushing a yes vote on Prop 40 (a group that includes every major newspaper in the state) argue that, while the new lines may not be perfect, they’re a whole lot better than the ones drawn under the old system, which promoted the protection of incumbents more than it did the accurate representation the population within each district.
On the other side....well...at this point, there is no other side. Republicans were hoping to overturn the new districts for 2012. However, since the state Supreme Court ruled the current lines would stand for 2012 no matter what happened, the groups initially pushing the measure have suspended their campaign and have stopped urging citizens to vote no.